Hydroxyalkylcysteine derivative and expectorant containing the same

ABSTRACT

Novel hydroxyalkylcysteine derivatives of the following formula (I) and an expectorant comprising the same are disclosed. ##STR1## wherein n represents an integer of 5 to 24. The expectorant is stabile, has little side effects and toxicity, and exhibits an excellent expectorant effect.

BACKGROUND OF THE INVENTION

1. Field of the Invention:

The present invention relates to a novel hydroxyalkylcysteine derivativeand an expectorant comprising the hydroxyalkylcysteine derivative as anactive ingredient.

2. Description of the Background:

Up to the present time, S-(2-hydroxyethyl)-L-cysteine [Journal ofPharmaceutical Sciences, 50, 312 (1961)] andS-(3-hydroxypropyl)-L-cysteine [Biochem. J., 100, 362 (1966)] are knownas hydroxyalkylcysteine derivatives. However, all that has been reportedconcerning their pharmacological effects is thatS-(2-hydroxyethyl)-L-cysteine has anti-seborrheic activity (West GermanLaid-open Patent No. 2,219,726) and that S-(3-hydroxypropyl)-L-cysteineis effective against anti-cholesterolemia and arteriosclerosis (U.S.Pat. No. 3,892,852).

On the other hand, cysteine derivatives such as carbocysteine,N-acetylcysteine, cysteine ethyl ester hydrochloride, and the like arebeing used as expectorants.

The cysteine derivatives described above when used in expectorants arenot completely satisfactory, particularly both N-acetylcysteine andethyl ester hydrochloride have the problems of strong toxicity andchemical instability.

Therefore, the development of an expectorant possessing stability,little side effects and toxicity, as well as an excellent expectoranteffect, has been desired.

In view of such circumstances, the inventors of the present inventionsynthesized a number of compounds and examined their pharmacologicaleffects. As a result of these investigations, it was found that thehydroxyalkylcysteine derivative shown by the following formula (I)fulfilled the above conditions and possessed an excellent expectoranteffect.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide ahydroxyalkylcysteine derivative represented by the following formula(I), ##STR2## wherein n represents an integer of 5 to 24.

Another object of the present invention is to provide an expectorantcomprising a hydroxyalkylcysteine derivative represented by said formula(I) as an active ingredient.

Other objects, features and advantages of the invention will hereinafterbecome more readily apparent from the following description.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS

In formula (I) above, n is an integer between 5 and 24, preferablybetween 5 and 10, and most preferably between 5 and 7.

Compound (I) of the present invention is prepared by the reactioninvolving a substituted alkyl alcohol (II) and cysteine (III) accordingto the following reaction formula, ##STR3## wherein X represents ahalogen atom, a tosyloxy group, or a methanesulfonyloxy group, and n isan integer defined above.

This method is carried out by reacting 1 mol of a compound (III) per1-1.2 mols of a compound (II) for 4-24 hours in an appropriate solventat a pH of about 9 using an alkali at room temperature, or if required,with heating.

Sodium bicarbonate, potassium carbonate, sodium carbonate, potassiumhydroxide, or sodium hydroxide can be used as an alkali. Water, awater-methanol solvent, or a water-ethanol solvent are desirable as thesolvent.

After the reaction is completed, the reaction mixture is washed with anorganic solvent (ether, ethyl acetate, chloroform, methylene chloride,or the like) and the pH of the aqueous layer is adjusted to between 4and 5 using hydrochloric acid or the like. If crystals precipitate out,they are collected by filteration and refined by recrystallization, orthe like. In the case where the crystals do not precipitate out, theaqueous layer is concentrated under reduced pressure and the residue isextracted using absolute methanol or the like. After concentrating theextract, ether is added to precipitate crystals, which are then purifiedby recrystallization or the like. Alternatively, crystals are producedfrom the residue with acetone and then purified by ion-exchange columnchromatography or by recrystallization. Compound (I) of the presentinvention is obtained using these methods.

Hereinafter are presented experimental examples to illustrate theexpectorant effect of Compound (I) of the present invention. Theseexamples are given for illustration of the invention and are notintended to be limiting thereof.

EXPERIMENTAL EXAMPLES

Test Method:

The expectorant effect was investigated based on the method of Sakuno[Manchurian Medical Journal, 33, 779 (1940)].

The test compound was suspended or dissolved in an aqueous solution of0.5 % carboxymethylcellulose sodium (CMC-Na). The solution wasadministered orally to rabbits at 500 mg/kg. At the same time, 1 mg/kgof a 0.6% phenol-sulfonphthalein (PSP) injection solution wasadministered into the ear vein of the rabbits. Thirty minutes later, thecarotid artery was severed and the rabbits were sacrificed byexsanguination. A cannula was placed into the trachea and a heated (38°C.) aqueous solution of 5% sodium bicarbonate (12.5 ml/kg) was infusedthrough cannula. After leaving for 10 mitutes, the infused solution wasslowly drawn out and then infused again. This procedure was repeated atotal of 3 times. The final solution collected was centrifuged at 10,000rpm for 30 minutes at 4° C. After adjusting the pH of the supernatantthus obtained to 8.0 with 1 N hydrochloric acid. the absorbance wasmeasured using a spectrophotometer at a wavelength of 557 nm in order toassay the amount of PSP. The amount of PSP was measured in the same wayas described above in the control group after orally administering 10ml/kg of an aqueous solution of 0.5% CMC-Na. The expectorant effect ofthe test compound was judged by the rate of increase in the amount ofPSP which effused into the respiratory tract.

The rate of increase in PSP amount was calculated according to thefollowing formula,

    Rate of increase in PSP amount (%)=(S-C)/C×100

wherein S is the amount of PSP in the test compound group and C is theamount of PSP in the group given 0.5% CMC-Na (control group).

Test Results:

The results are presented in Table 1.

                  TABLE 1                                                         ______________________________________                                                     PSP concentration                                                                           Rate of increase                                   Test compound                                                                              (μg/ml)    in PSP (%)                                         ______________________________________                                        Compound 1   0.91          98                                                 Compound 2   0.80          75                                                 Carbocysteine                                                                              0.57          23                                                 Control      0.46          --                                                 ______________________________________                                         Compound 1: S--(5hydroxypentyl)-L-cysteine                                    Compound 2: S--(6hydroxyhexyl)-L-cysteine                                

As can be seen from Table 1, compared to the control group, rabbits towhich Compound (I) was given showed a significant increase in the amountof PSP in the airway, thus evidencing that the compounds of thisinvention possess an excellent expectorant effect.

In addition, the toxicity of the compounds of formula (I) was extremelylow. In particular, the values for acute toxicity (LD₅₀) of the Compound(I) in which n =5 in formula (I) were greater than 10 g/kg when orallyadministered to mice or rats.

When Compound (I) is used as an expectorant the dose is differentdepending upon the administration route or the symptoms. However, in thecase of oral administration in normal adults, a daily administration of0.1-5 g once or over several doses is desirable, while for non-oraladministration, the daily dose range is 0.02-1 g, also either given as asingle dose or over several doses.

The present expectorant can be given by either oral or non-oraladministration in any type of preparations. For oral administrationforms such as tablets, capsules, powders, granules, troches or liquids,and the like can be used. For non-oral preparations hypodermicinjections, intramuscular or intravenous injections, mixed transfusionor infusion preparations, suppositories and the like are used. They canbe prepared by commonly known methods. In other words, tablets,capsules, powders, granules or troches can be prepared by formulatingappropriate combinations of Compound (I) and excipients such as starch,mannitol, lactose, or the like, binders such as carboxymethylcellulosesodium, hydroxypropylcellulose, or the like, disintegrators such ascrystalline cellulose, carboxymethylcellulose calcium, or the like,lubricants such as talc, magnesium stearate, or the like, and fluidityincreasing agents such as light anhydrous silicic acid or the like. Inaddition, aqueous liquid preparations and injection preparations can beprepared by using the water-soluble property of Compound (I).Suppositories can be prepared by dispersing Compound (I) into a commonlyused base material such as cacao butter, synthetic fats and oils, or thelike, and solidifying the mixture using common procedures.

Other features of the invention will become apparent in the course ofthe following description of the exemplary embodiments which are givenfor illustration of the invention and are not intended to be limitingthereof.

EXAMPLES Example 1

A small amount of water was added to 10.0 g (8.26×10⁻² mol) ofL-cysteine to make a suspension and the pH was adjusted to 9 by addingan aqueous solution of 2 N sodium hydroxide. To this solution, 11.1 g(9.1×10⁻² mol) of 5-chloro-1-pentanol was added, followed by stirringfor 4 hours at 60-70°C. Upon completion of the reaction, extraction withether was carried out 3 times, the pH of the aqueous layer was adjustedto 4 with 10% hydrochloric acid, and the solvent was evaporated underreduced pressure. The residue was repeatedly washed with acetone andthen pulverized. The resulting powder was subjected to ion-exchangechromatography (DOWEX-50W) and the fraction which eluted with a 2 Nammonia water was collected and concentrated under reduced pressure. Theresidue was recrystallized in a water/ethanol mixture and 12.7 g (yield:74%) of colorless crystals of S-(5-hydroxypentyl)-L-cysteine (CompoundNo. 1) was obtained.

m.p. 204-207°C. (decomposed).

1_(H-NMR) (D₂ O +DCl) δ ppm: 1.20-1.84 (6H, m), 2.48-2.76 (2H, m),3.04-3.24 (2H, m), 3.48-3.72 (2H, m), 4.34 (1H, m).

Example 2

10.0 g (8.26×10⁻² mol) of L-cysteine was suspended in a small amount ofwater and the pH of the solution was adjusted to 9 with an aqueoussolution of 2N sodium hydroxide. 13.1 g (9.1×10⁻² mol) of6-chloro-1-hexanol was then added and the solution was stirred for 6hours at 60-70°C. Upon completion of the reaction, ether extraction wascarried out 3 times. The pH of the aqueous layer was adjusted to 4.45with 10% hydrochloric acid and the solution was left standing overnight.The crystals which precipitated out were filtered, rinsed, andrecrystallized with water. The resulting material was 11.3 g (yield:62%) of colorless scale-shaped crystals ofS-(6-hydroxyhexyl)-L-cysteine, Compound No. 2 of the present invention.

m.p. 207-209°C. (decomposed).

1_(H-NMR) (D₂ O +DCl) δ ppm: 1.00-1.80 (8H, m), 2.40-2.76 (2H, m),3.04-3.18 (2H, m), 3.40-3.72 (2H, m), 4.20-4.44 (1H, m).

Example 3

13.2 g (yield: 64%) of colorless crystals ofS-(8-hydroxyoctyl)-L-cysteine (Compound No. 3) was obtained by reacting10.0 g (8.26×10⁻² mol) of L-cysteine and 15.42 g (9.1×10 mol) of8-chloro-1-octanol in the same way as described in Example 2.

m.p. 206-208°C. (decomposed).

1_(H-NMR) (D₂ O +DCl) δ ppm: 0.80-1.80 (12H, m), 2.44-2.76 (2H, m),3.04-3.28 (2H, m), 3.44-3.72 (2H, m), 4.20-4.48 (1H, m).

Example 4

2.0 g (1.65×10⁻² mol) of L-cysteine was suspended in a small amount ofwater and the pH of the suspension was adjusted to 9 with an aqueoussolution of 2N sodium hydroxide. 18 ml of ethanol and 4.7 g (1.82×10⁻²mol) of 5-tosyloxy-1-pentanol were then added and the resulting mixturewas stirred all night at room temperature.

Upon completion of the reaction, the pH was adjusted to 4 with 10%hydrochloric acid and the solvent was evaporated under reduced pressure.The residue was pulverized after repeated washing withacetone-chloroform. The resulting powder was subjected to ion-exchangechromatography (Dowex-50W) and eluted with 2 N ammonia water. Thefraction which eluted was collected and concentrated under reducedpressure. The residual material was recrystallized in water-ethanol toobtain 2.46 g (yield: 72%) of colorless crystals ofS-(5-hydroxypentyl)-L-cysteine (Compound No. 1).

Example 5

The compounds of the present invention were prepared from the rawmaterial, compounds (II), shown in Table 2, in the same manner as inExamples 1-4.

                  TABLE 2                                                         ______________________________________                                        Raw Material  Compounds of this Invention                                     Compound (II) Compound (I)                                                    ______________________________________                                        7-chloro-1-heptanol                                                                         S--(7-hydroxyheptyl)-L-cysteine                                 9-chloro-1-nonanol                                                                          S--(9-hydroxynonanyl)-L-cysteine                                10-bromo-1-decanol                                                                          S--(10-hydroxydecanyl)-L-cysteine                               11-bromo-1-undecanol                                                                        S--(11-hydroxyundecanyl)-L-cysteine                             12-bromo-1-dodecanol                                                                        S--(12-hydroxydodecanyl)-L-cysteine                             13-bromo-1-tridecanol                                                                       S--(13-hydroxytridecanyl)-L-cysteine                            14-chloro-1-  S--(14-hydroxytetradecanyl)-L-cysteine                          tetradecanol                                                                  15-chloro-1-  S--(15-hydroxypentadecanyl)-L-cysteine                          pentadecanol                                                                  16-chloro-1-hexadecanol                                                                     S--(16-hydroxyhexadecanyl)-L-cysteine                           17-chloro-1-  S--(17-hydroxyheptadecanyl)-L-cysteine                          heptadecanol                                                                  18-bromo-1-octadecanol                                                                      S--(18-hydroxyoctadecanyl)-L-cysteine                           19-chloro-1-  S--(19-hydroxynonadecanyl)-L-cysteine                           nonadecanol                                                                   20-chloro-1-eicosanol                                                                       S--(20-hydroxyeicosanyl)-L-cysteine                             5-iodo-2-pentanol                                                                           S--(4-hydroxypentyl)-L-cysteine                                 6-iodo-3-hexanol                                                                            S--(4-hydroxyhexyl)-L-cysteine                                  7-iodo-2-heptanol                                                                           S--(4-hydroxyheptyl)-L-cysteine                                 ______________________________________                                    

FORMULATION EXAMPLES Example 6 (tablets)

Tablets were prepared using known procedures and the followingingredients. These tablets can be prepared into film coated or sugarcoated tablets.

    ______________________________________                                        Compound No. 1       250    mg                                                Crystalline cellulose                                                                              50     mg                                                Lactose              40     mg                                                Hydroxypropylcellulose                                                                             15     mg                                                Magnesium stearate   5      mg                                                Total                360    mg/tablet                                         ______________________________________                                    

Example 7 (capsules)

Granules were prepared using known procedures and the followingingredients, and then filled into No. 1 capsules.

    ______________________________________                                        Compound No. 2       125    mg                                                Crystalline cellulose                                                                              87     mg                                                Light anhydrous silicic acid                                                                       35     mg                                                Talc                 3      mg                                                Total                250    mg/capsule                                        ______________________________________                                    

Example 8 (granules)

Granules were prepared according to known procedures using the followingingredients.

    ______________________________________                                        Compound No. 3         250 mg                                                 Lactose                600 mg                                                 Starch                 135 mg                                                 Polyvinylpyrrolidone   15 mg                                                  Total                  1,000 mg                                               ______________________________________                                         Example 9 (troche)

Troches were prepared according to known procedures using the followingingredients.

    ______________________________________                                        Compound No. 1      250    mg                                                 Magnesium stearate  20     mg                                                 Polyvinylpyrrolidone                                                                              50     mg                                                 Sucrose             680    mg                                                 Total               1,000  mg/troche                                          ______________________________________                                    

Example 10 (powder)

Powder was prepared according to known procedures using the followingingredients.

    ______________________________________                                        Compound No. 2          250 mg                                                Light anhydrous silicic acid                                                                           30 mg                                                Lactose                 250 mg                                                Starch                   70 mg                                                Total                   600 mg                                                ______________________________________                                    

Example 11 (syrup)

Syrup was prepared according to known procedures using the followingingredients.

    ______________________________________                                        Compound No. 3         200 mg                                                 Ethyl paraoxybenzoate  1 mg                                                   Sucrose                5,000 mg                                               ______________________________________                                    

Syrup was produced by adding purified water to a volume of 10 ml.

Example 12 (suppositories)

Suppositories were prepared according to known procedures by forming andsolidifying after the following ingredients were melted and stirred.

    ______________________________________                                        Compound No. 1     250    mg                                                  Cacao butter       1,250  mg                                                  Total              1,500  mg/suppository                                      ______________________________________                                    

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

What is claimed is:
 1. A hydroxyalkylcysteine derivative of thefollowing formula (I), ##STR4## wherein n represents an integer of 5 to24.
 2. An expectorant comprising a hydroxyalkylcysteine derivative ofthe following formula (I), ##STR5## wherein n represents an integer of 5to 24 and a carrier therefor.